Detergent injection methods for carbon dioxide cleaning apparatus

ABSTRACT

A system for the controlled addition of detergent formulations and the like to a carbon dioxide cleaning apparatus comprises: (a) a high pressure wash vessel; (b) an auxiliary vessel; (c) a drain line connecting the auxiliary vessel to the wash vessel; (d) optionally but preferably, a separate vent line connecting the auxiliary vessel to the wash vessel; (e) a detergent reservoir; and (f) a detergent supply line connecting the detergent reservoir to the auxiliary vessel. An advantage of this apparatus is that, because the detergent formulation can be pumped into the auxiliary vessel in a predetermined aliquot or amount, which predetermined aliquot or amount can then be transferred into the wash vessel where it combines with the liquid carbon dioxide cleaning solution, the detergent formulation can be added to the cleaning solution in a more controlled or accurate manner. An alternate embodiment adapted for the addition of aqueous detergent formulations and the like to a carbon dioxide dry cleaning system under turbulent conditions comprises: (a) a high pressure wash vessel; (b) a filter; (c) a carbon dioxide cleaning solution drain line interconnecting the wash vessel to the filter; (d) a carbon dioxide cleaning solution supply line connecting the filter to the wash vessel; (e) a first high pressure pump (i.e., a pump that is capable of pumping liquid solutions comprising liquid carbon dioxide) operably connected to the drain line; (f) a detergent formulation reservoir; (g) a detergent formulation supply line connecting the reservoir to the carbon dioxide cleaning solution supply line; and (h) a second high pressure pump operably connected to the detergent formulation supply line for transferring detergent formulation from the detergent formulation reservoir into the carbon dioxide cleaning solution under turbulent conditions.

RELATED APPLICATIONS

[0001] This application is a continuation-in-part of commonly owned,copending U.S. patent application Ser. No. 09/312,556, Filed May 14,1999, the disclosure of which is incorporated by reference herein in itsentirety.

FIELD OF THE INVENTION

[0002] The present invention relates to methods for carrying out the drycleaning of fabrics (e.g., garments) in liquid carbon dioxide, andparticularly relates to methods and apparatus for adding detergentformulations to liquid carbon dioxide dry cleaning systems.

BACKGROUND OF THE INVENTION

[0003] Many traditional solvent-based cleaning applications can sufferfrom poor performance on aqueous born soils. A significant portion ofthe soils found in conventional dry cleaning can be categorized aspartially or wholly water-soluble. Water-in-oil surfactants have beendeveloped that effectively disperse water to yield optically clearhomogeneous mixtures. These dispersions can effectively dissolvewater-soluble soils, termed secondary solublization, if the proper wateractivity is achieved in a given cleaning solvent. Water activity,determined by a number of factors including temperature, the nature ofsolvent-solute interactions and the molar ratio of surfactant to water,is generally monitored in conventional dry cleaning by what is termed asrelative humidity. A cleaning bath with low relative humidity and hencelow water activity will not allow for secondary solublization of aqueousborn soils. Water exceeding a critical level can lead to non-dispersedbulk water that can be deleterious to certain garment types.

[0004] Carbon dioxide based dry cleaning is a new technology that hasonly recently been commercially implemented. Like conventional drycleaning solvents watersoluble soils are not inherently soluble inliquefied carbon dioxide. Surfactant systems that enable the waterbearing nature of liquid carbon dioxide have been disclosed in thepatent and open literature. Under certain conditions these systems havedemonstrated that water-soluble materials can be dissolved and dispersedin a liquid carbon dioxide medium.

[0005] Many conventionally used water-in-oil surfactants applied to drycleaning solvents are not compatible with liquid CO₂ solvent systems.Surfactants containing what is termed to be “CO₂-philic” function havebeen proven to be useful in the emulsification of water in CO₂. Theexclusive use of some of these materials can be cost prohibitive formany applications. The case for dissolution of water-soluble materialsin CO₂ can be further complicated by the reversible reaction betweenwater and carbon dioxide producing carbonic acid. This weak acid whichreverts back to water and carbon dioxide as pressure is lowered and CO₂is removed can have substantial implications on water activity in CO₂.Lower water activity can effect the ability of the CO₂ cleaning fluid todissolve water-soluble soils. Certain pH buffers have been used inliquid and supercritical CO₂ to control the pH of aqueous micro andmacro-domains and in turn augment water activity. Attempts to raise thewater activity in current processes by the addition of bulk water canfail because of the inability of the CO₂ and surfactant combinations tosufficiently stabilize the water. Bulk water phase-separated from liquidCO₂ cleaning fluids and conventional cleaning fluids can havesubstantial detrimental effects on many dry clean only fabrics.

[0006] Not all stains are water soluble. Indeed, a significant number ofstains that must be cleaned in a dry cleaning operation are hydrophobic.Thus, in addition to aqueous detergent formulations, it is alsodesirable to have a means for adding low water content detergentformulations to carbon dioxide dry cleaning systems.

[0007] U.S. Pat. No. 5,858,022 to Romack et al. and U.S. Pat. No.5,683,473 to Jureller et al. (see also U.S. Pat. No. 5,683,977 toJureller et al.) describe carbon dioxide dry cleaning methods andcompositions. Our co-pending U.S. patent application Ser. No. 09/047,013of McClain et al., filed Mar. 24, 1998, describes carbon dioxide drycleaning apparatus. Dry cleaning apparatus is also described in U.S.Pat. No. 5,467,492 to Chao et al. U.S. Pat. No. 5,651,276 to Purer etal., and U.S. Pat. No. 5,784,905 to Townsend et al. It will be seen thatthere is a need for better ways to add detergent formulations to thecarbon dioxide during operation of the apparatus.

SUMMARY OF THE INVENTION

[0008] A first aspect of the present invention is system for thecontrolled addition of detergent formulations and the like to a carbondioxide cleaning apparatus. The system preferably comprises:

[0009] (a) a high pressure wash vessel;

[0010] (b) an auxiliary vessel;

[0011] (c) a drain line connecting the auxiliary vessel to the washvessel;

[0012] (d) optionally but preferably, a separate vent line connectingthe auxiliary vessel to the wash vessel;

[0013] (e) a detergent reservoir; and

[0014] (f) a detergent supply line connecting the detergent reservoir tothe auxiliary vessel.

[0015] An advantage of this apparatus is that, because the detergentformulation can be pumped into the auxiliary vessel in a predeterminedaliquot or amount, which predetermined aliquot or amount can then betransferred into the wash vessel where it combines with the liquidcarbon dioxide cleaning solution, the detergent formulation can be addedto the cleaning solution in a more controlled or accurate manner.

[0016] A second aspect of the present invention is a method for thecontrolled addition of a low-water content detergent formulation or thelike (e.g., a starch or size formulation) to a carbon dioxide drycleaning system. The method comprises:

[0017] (a) providing a carbon dioxide cleaning apparatus comprising awash vessel and a separate auxiliary vessel;

[0018] (b) reducing the pressure in the wash vessel and the auxiliaryvessel; then

[0019] (c) adding a detergent formulation to the auxiliary vessel, thedetergent (c) formulation comprising (i) at least 30 percent organicco-solvent, (ii) at least 1 percent surfactant; and (ii) not more than10 percent water (and preferably less than 10 percent water); then

[0020] (d) increasing the pressure in the wash vessel so that liquidcarbon dioxide can be pumped therethrough to clean articles in the washvessel; and then

[0021] (e) transferring the detergent formulation from the auxiliaryvessel to the wash vessel to facilitate the cleaning of articlestherein.

[0022] A third aspect of the present invention is a system for theaddition of aqueous detergent formulations and the like to a carbondioxide dry cleaning system under turbulent conditions. The systempreferably comprises:

[0023] (a) a high pressure wash vessel;

[0024] (b) a filter;

[0025] (c) a carbon dioxide cleaning solution drain line interconnectingthe wash vessel to the filter;

[0026] (d) a carbon dioxide cleaning solution supply line connecting thefilter to the wash vessel;

[0027] (e) a first high pressure pump (i.e., a pump that is capable ofpumping liquid solutions comprising liquid carbon dioxide) or otherliquid transfer means operably connected to or associated with the drainline;

[0028] (f) a detergent formulation reservoir;

[0029] (g) a detergent formulation supply line connecting the reservoirto the carbon dioxide cleaning solution supply line or drain line; and

[0030] (h) a second high pressure pump operably connected to thedetergent formulation supply line for transferring detergent formulationfrom the detergent formulation reservoir into the carbon dioxidecleaning solution under turbulent conditions.

[0031] An advantage of this apparatus is that it provides for theintroduction of detergent formulations and the like under turbulentconditions, which facilitates the mixing of the formulations with theliquid carbon dioxide wash solution. Such a manner of introduction isparticularly advantageous when the detergent formulation is immiscible,wholly or in part, with the liquid carbon dioxide wash solution.

[0032] A fourth aspect of the present invention is a method for theaddition of aqueous detergent formulations and the like to a carbondioxide dry cleaning system under turbulent conditions. The method maybe carried out with an apparatus as described immediately above. Themethod comprises:

[0033] (a) providing a carbon dioxide cleaning apparatus comprising awash vessel and a filter;

[0034] (b) pumping a continuous stream of liquid carbon dioxide cleaningsolution from the wash vessel through the filter and back to the washvessel to clean articles in the wash vessel; and

[0035] (c) adding a detergent formulation into the continuous stream ofliquid carbon dioxide (for example, at a point downstream of the filterand upstream of the wash vessel) to introduce the detergent formulationinto the continuous stream, with the detergent formulation comprising(i) at least 10 or preferably at least 20 percent water, and (ii) atleast 1 percent surfactant, so that water in the detergent formulationis dispersed in the liquid carbon dioxide prior to entry into the washvessel, without depletion in the filter.

[0036] The systems described above may be provided independently on acleaning apparatus, or may be combined together on a cleaning apparatusto provide the capability of both manners of detergent introduction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037]FIG. 1 schematically illustrates an apparatus for the controlledintroduction of detergent formulations into the wash vessel of a carbondioxide cleaning apparatus.

[0038]FIG. 2 schematically illustrates an apparatus for the introductionof detergent formulations into a carbon dioxide dry cleaning apparatusunder turbulent conditions.

[0039]FIG. 3 illustrates a combined apparatus which separately providesfor both the controlled introduction of detergent formulations into thewash vessel of a carbon dioxide cleaning apparatus, and for theintroduction of detergent formulations into the carbon dioxide drycleaning apparatus under turbulent conditions.

[0040]FIG. 4 is a further embodiment of the present invention similar tothat of FIG. 1, with an alternate drain control system.

[0041]FIG. 5 is a further embodiment of the present invention, withseveral alternate drain control system.

DETAILED DESCRIPTION OF THE INVENTION

[0042] The term “clean” as used herein refers to any removal of soil,dirt, grime, or other unwanted material, whether partial or complete.The invention may be used to clean nonpolar stains (i.e., those whichare at least partially made by nonpolar organic compounds such as oilysoils, sebum and the like), polar stains (i.e., hydrophilic stains suchas grape juice, coffee and tea stains), compound hydrophobic stains(i.e., stains from materials such as lipstick and candle wax), andparticular soils (i.e., soils containing insoluble solid components suchas silicates, carbon black, etc.).

[0043] Articles that can be cleaned by the method of the presentinvention are, in general, garments and fabrics (including woven andnon-woven) formed from materials such as cotton, wool, silk, leather,rayon, polyester, acetate, fiberglass, furs, etc., formed into itemssuch as clothing, work gloves, rags, leather goods (e.g., handbags andbrief cases), etc.

[0044] Detergent formulations described herein are combined with liquidcarbon dioxide (which may also contain surfactants and other previouslyadded ingredients) to provide liquid carbon dioxide-based dry cleaningcompositions. Such compositions typically comprise:

[0045] (a) from zero, 0.02, 0.05 or 0.1 to 5 or 10 percent (morepreferably from 0.1 to 4 percent) water;

[0046] (b) carbon dioxide (to balance; typically at least 30 percent);

[0047] (c) surfactant (preferably from 0.1 or 0.5 percent to 5 or 10percent total, which may be comprised of one or more differentsurfactants); and

[0048] (d) from 0.1 to 50 percent (more preferably 1, 2 or 4 percent to30 percent) of an organic co-solvent.

[0049] Percentages herein are expressed as percentages by weight unlessotherwise indicated. The composition is provided in liquid form atambient, or room, temperature, which will generally be between zero and50° Centigrade. The composition is held at a pressure that maintains itin liquid form within the specified temperature range. The cleaning stepis preferably carried out with the composition at ambient temperature.

[0050] 1. Organic Co-solvents

[0051] The organic co-solvent is, in general, a hydrocarbon co-solvent.Typically the co-solvent is an alkane co-solvent, with C₁₀ to C₂₀linear, branched, and cyclic alkanes, and mixtures thereof (preferablysaturated) currently preferred. The organic co-solvent preferably has aflash point above 140° F., and more preferably has a flash point above170° F. The organic co-solvent may be a mixture of compounds, such asmixtures of alkanes as given above, or mixtures of one or more alkanes.Additional compounds such as one or more alcohols (e.g., from 0 or 0.1to 5% of a C1 to C15 alcohol (including diols, triols, etc.)) differentfrom the organic co-solvent may be included with the organic co-solvent.

[0052] Examples of suitable co-solvents include, but are not limited to,aliphatic and aromatic hydrocarbons, and esters and ethers thereof,particularly mono and di-esters and ethers (e.g., EXXON ISOPAR L, ISOPARM, ISOPAR V, EXXON EXXSOL, EXXON DF 2000, CONDEA VISTA LPA-170N, CONDEAVISTA LPA-210, cyclohexanone, and dimethyl succinate), alkyl and dialkylcarbonates (e.g., dimethyl carbonate, dibutyl carbonate, di-t-butyldicarbonate, ethylene carbonate, and propylene carbonate), alkylene andpolyalkylene glycols, and ethers and esters thereof (e.g., ethyleneglycol-n-butyl ether, diethylene glycol-n-butyl ethers, propylene glycolmethyl ether, dipropylene glycol methyl ether, tripropylene glycolmethyl ether, and dipropylene glycol methyl ether acetate), lactones(e.g., (gamma)butyrolactone, (epsilon)caprolactone, and (delta)dodecanolactone), alcohols and diols (e.g., 2-propanol,2-methyl-2-propanol, 2-methoxy-2-propanol, 1-octanol, 2-ethyl hexanol,cyclopentanol, 1,3-propanediol, 2,3-butanediol,2-methyl-2,4-pentanediol) and polydimethylsiloxanes (e.g.,decamethyltetrasiloxane, decamethylpentasiloxane, andhexamethyldisloxane), etc.

[0053] 2. Surfactants

[0054] Any surfactant can be used to carry out the present invention,including both surfactants that contain a CO₂-philic group (such asdescribed in PCT Application WO96/27704) linked to a CO₂-phobic group(e.g., a lipophilic group) and (more preferably) conventionalsurfactants, or surfactants that do not contain a CO₂-philic group(i.e., surfactants that comprise a hydrophilic group linked to ahydrophobic (typically lipophilic) group). A single surfactant may beused, or a combination of surfactants may be used.

[0055] Numerous surfactants are known to those skilled in the art. See,e.g., McCutcheon's Volume 1: Emulsifiers & Detergents (1995 NorthAmerican Edition) (MC Publishing Co., 175 Rock Road, Glen Rock, N.J.07452). Examples of the major surfactant types that can be used to carryout the present invention include the: alcohols, alkanolamides,alkanolamines, alkylaryl sulfonates, alkylaryl sulfonic acids,alkylbenzenes, amine acetates, amine oxides, amines, sulfonated aminesand amides, betaine derivatives, block polymers, carboxylated alcohol oralkylphenol ethoxylates, carboxylic acids and fatty acids, diphenylsulfonate derivatives, ethoxylated alcohols, ethoxylated alkylphenols,ethoxylated amines and/or amides, ethoxylated fatty acids, ethoxylatedfatty esters and oils, fatty esters, fluorocarbon-based surfactants,glycerol esters, glycol esters, hetocyclic-type products, imidazolinesand imidazoline derivatives, isethionates, lanolin-based derivatives,lecithin and lecithin derivatives, lignin and lignin derivatives, maleicor succinic anhydrides, methyl esters, monoglycerides and derivatives,olefin sulfonates, phosphate esters, phosphorous organic derivatives,polyethylene glycols, polymeric (polysaccharides, acrylic acid, andacrylamide) surfactants, propoxylated and ethoxylated fatty acidsalcohols or alkyl phenols, protein-based surfactants, quaternarysurfactants, sarcosine derivatives, silicone-based surfactants, soaps,sorbitan derivatives, sucrose and glucose esters and derivatives,sulfates and sulfonates of oils and fatty acids, sulfates andsulfonates, ethoxylated alkylphenols, sulfates of alcohols, sulfates ofethoxylated alcohols, sulfates of fatty esters, sulfonates of benzene,cumene, toluene and xylene, sulfonates of condensed naphthalenes,sulfonates of dodecyl and tridecylbenzenes, sulfonates of naphthaleneand alkyl naphthalene, sulfonates of petroleum, sulfosuccinamates,sulfosuccinates and derivatives, taurates, thio and mercaptoderivatives, tridecyl and dodecyl benzene sulfonic acids, etc.

[0056] Additional examples of surfactants that can be used to carry outthe present invention include alcohol and alkylphenol polyalkylethers(e.g., TERGITOL 15-S-3™ secondary alcohol ethoxylate, TRITONX-207™ dinonylphenol ethoxylate, NEODOL 91-2.5™ primary alcoholethoxylate, RHODASURF BC-410™ isotridecyl alcohol ethoxylate, RHODASURFDA-630™ tridecyl alcohol ethoxylate) alkylaryl carbonates, includingsalts and derivatives thereof (e.g., acetic acid, MARLOWET 4530™dialkylphenol polyethylene glycol acetic acid, MARLOWET 1072™ alkylpolyethylene glycol ether acetic acid), alkoxylated fatty acids (e.g.,NOPALCOL 1-TW™ diethylene glycol monotallowate, TRYDET 2600™polyoxyethylene (8) monostearate), alkylene oxide block copolymers(e.g., PLURONIC™ and TETRONIC™ products), acetylenic alcohols and diols(e.g., SURFYNOL™ and DYNOL™ products), mono- and di-esters ofsulfosuccinic acid (e.g., AEROSOL OT™ sodium dioctyl sulfosuccinate,AEROSOL IB-45™ sodium diisobutyl sulfosuccinate, MACKANATE DC-50™dimethicone copolyol disodium sulfosuccinate, SOLE TERGE-8™ oleic acidisopropanolamide monoester of sodium sulfosuccinate), sulfosuccinamicacid and esters thereof (e.g. AEROSOL 18™ disodium-N-octadecylsulfosucciniamate, AEROSOL 22™ tetrasodium N-(1,2-dicarboxyethyl)-Noctadecyl sulfosuccinamate) sorbitan esters including derivativesthereof (e.g., SPAN 80™ sorbitan monoleate, ALKAMULS 400-DO™ sorbitandioleate, ALKAMULS STO™ sorbitan trioleate, TWEEN 81™ polyoxyethylene(5) sorbitan monoleate, TWEEN 21™ polyoxyethylene (4) sorbitanmonolaurate), isothionates including derivatives thereof (e.g., GEROPONAC-270™ sodium cocoyl isothionate), polymeric alkylaryl compounds andlignins, including derivatives thereof (e.g. LIGNOSITE 50™ calciumlignosulfonate), alkylaryl sulfonic acids and salts thereof (e.g.,CALIMULSE EM-99™ branched dodecylbenzene sulfonic acid, WITCONATE C-50H™sodium dodecylbenzene sulfonate, WITCONATE P10-59™ amine salt ofdodecylbenzene sulfonate), sulfonated amines and amides (e.g., CALIMULSEPRS™ isopropylamine sulfonate), Betaine and sultaine derivatives, andsalts thereof (e.g., lauryl sulfobetaine,dodecyldimethyl(3-sulfopropyl)ammonium hydroxide, FOAMTAIN CAB-A™cocamidopropyl betaine ammonium salt, FOAMTAINE SCAB™ cocamidopropylhydroxy sultaine), e.g., imidazolines including derivatives thereof(e.g., MONOAZOLINE O™ substituted imidazoline of oleic acid, MONOAZOLINET™ substituted imidazoline of Tall Oil), oxazolines includingderivatives thereof (e.g., ALKATERGE E™ oxazoline derivative, ALKATERGET-IV™ ethoxylated oxazoline derivative), carboxylated alcohol oralkylphenol ethoxylates including derivatives thereof (e.g., MARLOSOLOL™ oleic acid polyglycol ester), diphenyl sulfonates includingderivatives thereof (e.g., DOWFAX™ detergent diphenyl oxide disulfonate,DOWFAX™ dry detergent: sodium n-hexadecyl diphenyl oxide disulfonate,DOWFAX™ Dry hydrotrope: sodium hexyl diphenyloxide disulfonate)fluorinated surfactants (e.g., FLUORAD FC-120™ ammonium perfluoroalkylsulfonate, FLUORAD FC-135™ fluoroalkyl quaternary ammonium iodides,FLUORAD FC-143™ ammonium perfluoroalkyl carboxylates), lecithinsincluding lecithin derivatives (e.g., ALCOLEC BS™ soy phosphatides),phosphate esters (e.g., ACTRAFOS SA-216™ aliphatic phosphate ester,ACTRAFOS 110™ phosphate ester of complex aliphatic hydroxyl compound,CHEMPHOS TC-310™ aromatic phosphate ester, CALGENE PE-112N™ phosphatedmono- and diglycerides), sulfates and sulfonates of fatty acids (e.g.,ACTRASOL PSR™ sulfated castor oil, ACTRASOL SR75™ sulfated oleic acid),sulfates of alcohols (e.g., DUPONOL C™ sodium lauryl sulfate, CARSONOLSHS™ sodium 2-ethyl-1-hexyl sulfate, CALFOAM TLS-40™ triethanolaminelauryl sulfate), sulfates of ethoxylated alcohols (e.g., CALFOAM ES-301™sodium lauryl ether sulfate), amines, including salts and derivativesthereof (e.g., Tris(hydroxymethyl)aminomethane, ARMEEN™ primaryalkylamines, ARMAC HT™ acetic acid salt of N-alkyl amines) amidesulfonates (e.g., GEROPON TC-42™ sodium N-coconut acid-N-methyl taurate,GEROPON TC 270™ sodium cocomethyl tauride), quaternary amines, includingsalts and derivatives thereof (e.g., ACCOSOFT 750™ methyl bis (soyaamidoethyl)-N-polyethoxyethanol quaternary ammonium methyl sulfate,ARQUAD™ N-alkyl trimethyl ammonium chloride, ABIL QUAT 3272™ diquatemarypolydimethylsiloxane), amine oxides (e.g., AMMONYX CO™ cetyldimethylamine oxide, AMMONYX SO™ stearamine oxide), esters of glycerol,sucrose, glucose, sarcosine and related sugars and hydrocarbonsincluding their derivatives (e.g., GLUCATE DO™ methyl glucosidedioleate, GLICEPOL 180™ glycerol oleate, HAMPOSYL AL-30™ ammoniumlauroyl sarcosinate, HAMPOSYL M™ N-myristoyl sarcosine, CALGENE CC™propylene glycol dicaprylate/dicaprate), polysaccharides includingderivatives thereof (e.g., GLUCOPON 225 DK™ alkyl polysaccharide ether),protein surfactants (e.g., AMITER LGS-2™ dioxyethylene stearyl etherdiester of N-lauroyl-L-glutamic acid, AMISOFT CA™ cocoyl glutamic acid,AMISOFT CS 11™ sodium cocoyl glutamate, MAYTEIN KTS™ sodium/TEA laurylhydrolyzed keratin, MAYPON 4C™ potassium cocoyl hydrolyzed collagen),and including thio and mercapto derivatives of the foregoing (e.g.,ALCODET™ polyoxyethylene thioether, BURCO TME™ ethoxylated dodecylmercaptan), etc.

[0057] Thus the present invention may be carried out using conventionalsurfactants, including but not limited to the anionic or nonionicalkylbenzene sulfonates, ethoxylated alkylphenols and ethoxylated fattyalcohols described in Schollmeyer German Patent Application DE 39 04514A1, that are not soluble in liquid carbon dioxide and which could not beutilized in the invention described in U.S. Pat. No. 5,683,473 toJureller et al. or U.S. Pat. No. 5,683,977 to Jureller et al.

[0058] As will be apparent to those skilled in the art, numerousadditional ingredients can be included in the detergent formulations,including whiteners, softeners, sizing, starches, enzymes, hydrogenperoxide or a source of hydrogen peroxide, fragrances, etc.

[0059] 3. Cleaning Apparatus

[0060] Any suitable cleaning apparatus may be employed, including bothhorizontal drum and vertical drum apparatus. When the drum is ahorizontal drum, the agitating step is carried out by simply rotatingthe drum. When the drum is a vertical drum it typically has an agitatorpositioned therein, and the agitating step is carried out by moving(e.g., rotating or oscillating) the agitator within the drum. A vaporphase may be provided by imparting sufficient shear forces within thedrum to produce cavitation in the liquid dry-cleaning composition.

[0061] U.S. Pat. No. 5,858,022 to Romack et al. and U.S. Pat. No.5,683,473 to Jureller et al. (see also U.S. Pat. No. 5,683,977 toJureller et al.) describe carbon dioxide dry cleaning methods andcompositions which may be used to carry out the present. invention. Allissued and pending United States Patent references referred to hereinare to be incorporated by reference herein in their entirety.

[0062] Our co-pending U.S. patent application Ser. No. 09/047,013 ofMcClain et al., filed Mar. 24, 1998, describes carbon dioxide drycleaning apparatus that may be used to carry out the present invention.

[0063] In an alternate embodiment of the invention, agitation may beimparted by means of jet agitation as described in U.S. Pat. No.5,467,492 to Chao et al., the disclosure of which is incorporated hereinby reference. As noted above, the liquid dry cleaning composition ispreferably an ambient temperature composition, and the agitating step ispreferably carried out at ambient temperature, without the need forassociating a heating element with the cleaning apparatus.

[0064] Finally, dry cleaning apparatus that may be used to carry out thepresent invention is also described in U.S. Pat. No. 5,651,276 to Pureret al. and U.S. Pat. No. 5,784,905 to Townsend et al.

[0065] 4. Low-Water Detergent Formulations

[0066] As noted above, in one embodiment of the invention the detergentformulation is low in water content, or substantially nonaqueous.Preferred low-water content detergent formulations for carrying out thepresent invention typically comprise, by weight:

[0067] (a) at least 10 percent organic co-solvent (and preferably atleast 40, 50, 60 or 80 percent organic co-solvent or more, up to 99percent organic co-solvent or more) (which may be one or more organicsolvents);

[0068] (b) at least 0.1 percent surfactant (preferably 1, 2 or 4 to 5,10 or 15 percent surfactant or more); and

[0069] (c) not more than 5 or 10 percent water. In some cases, theformulation may be free of water (or non-aqueous), or may contain up tonot more than 1, 2, 3 or 4 percent water.

[0070] Additional adjuncts useful in these formulations includewhiteners, brighteners, fragrances, sizing agents, coatings, pH buffers,bleaches, enzymes, alcohols, peroxides, softeners, etc.

[0071] 5. Apparatus for Adding Low-Water Detergent Formulations

[0072] As noted above, the present invention provides a system for thecontrolled addition of detergent formulations and the like to a carbondioxide cleaning apparatus. As illustrated in FIG. 1, the systempreferably comprises a high pressure wash vessel 11 (i.e., a wash vesselthat is capable of containing liquid carbon dioxide), an auxiliaryvessel 12, and a drain line 13 connecting the auxiliary vessel to thewash vessel. The auxiliary vessel is positioned above the wash vessel sothat the contents of the auxiliary vessel can be transferred by gravityto the wash vessel. Alternatively the auxiliary vessel could bepositioned below the wash vessel and the contents thereof transferred tothe wash vessel by means of a pump. Optionally, but preferably, a ventline 14 connects the auxiliary vessel to the wash vessel to providegas-side communication therebetween (i.e., the point of connection ofthe vent line to each vessel is above the liquid-fill level therein).This facilitates the transfer of the contents of the auxiliary vessel tothe wash vessel.

[0073] A detergent reservoir 15 is provided, and a detergent supply line16 is provided connecting the detergent reservoir to the auxiliaryvessel. Valves 17, 18 are provided to control the system, as discussedin greater detail below.

[0074] A pump 19, which is preferably an inexpensive, low pressure pump,is provided to fill the auxiliary vessel from the detergent reservoir.Other mechanisms could also be employed. For example, the detergentreservoir could be positioned above the auxiliary vessel and theauxiliary vessel gravity filled from the reservoir.

[0075] The wash vessel may contain a rotating basket driven by anysuitable drive means 20, including but not limited to a turbine drive, adirect motor drive, an internal or external electric motor, etc. Drivemechanisms are discussed in greater detail in the patents and patentapplications referenced above.

[0076] In operation, the aforesaid apparatus provides a method for thecontrolled addition of a low-water content detergent formulation or thelike (e.g., a starch or size formulation) to a carbon dioxide drycleaning system. In general, valve 17 is closed to fill the auxiliaryvessel and opened to empty the auxiliary vessel into the wash tank.Valve 18 is opened to fill the auxiliary vessel, but closed when thepressure in the wash tank is increased to prevent back pressure fromreaching the detergent reservoir. The method involves, initially,reducing the pressure in the wash vessel and the auxiliary vessel. Thepressure may be wholly or partially reduced, but is preferably reducedto atmospheric pressure at the time the wash vessel is opened to removearticles such as clothing or fabric therein and/or insert new articlesto be cleaned. Then, a detergent formulation or the like such asdescribed above or below (and preferably a formulation that does notcontain more than 10 percent water), is transferred into the auxiliaryvessel from reservoir 15 by means of pump 19. Preferably, the pressurein the wash vessel is then increased so that liquid carbon dioxide canbe pumped therethrough to clean articles in the wash vessel. Thedetergent formulation is then transferred from the auxiliary vessel tothe wash vessel to facilitate the cleaning of articles therein. Liquidcarbon dioxide cleaning solution can be separately pumped into and/orcycled through the wash vessel, before or after the detergentformulation has been transferred from the auxiliary vessel to the washvessel.

[0077] 6. Aqueous Detergent Formulations

[0078] As noted above, the present invention discloses aqueous baseddetergent compositions and their method of introduction into liquidcarbon dioxide dry cleaning machines. The composition and method ofapplication of these materials provides for improved water-solublecleaning in carbon dioxide dry cleaning machines. These compositions areto be injected automatically or by choice into liquid carbon dioxidewash fluid during a cleaning cycle which may or may not containsurfactants, cosolvents, and other adjuncts previously disclosed. Themethod of injection is important in determining the effectiveness of theaqueous cleaning, as is the composition of the injected detergent.

[0079] The composition of the useful detergents is generally aqueous innature with water representing between 5 and 100% of the injectedmaterial, preferably between 50 and 98%. Formulations also containsurfactants that help disperse water once injected into the CO₂ washfluid, help wet the surface of the articles to be cleaned, help lowerstatic interactions between soil and items to be cleaned, or helpdeplete water at the surface of items to be cleaned. Useful surfactantlevels are between 0 and 20%, preferably between 0 and 5%. Theformulations may also contain co-solvents useful in modifying thesolvent power of the CO₂, useful in quantities between 0 and 90%, moreuseful between 0 and 30%.

[0080] Preferred aqueous detergent formulations for carrying out thepresent invention typically comprise, by weight:

[0081] (a) at least 10 percent water (and preferably at least 40, 50, 60or 80 percent water or more, up to 99 percent water or more);

[0082] (b) at least 0.1 percent surfactant (preferably 1, 2 or 4 to 5,10 or 15 percent surfactant or more); and

[0083] (c) from zero, 1 or 2 to 5, 10, 20 or 40 percent of an organicco-solvent.

[0084] Additional adjuncts useful in these formulations includewhiteners, brighteners, alcohols, fragrances, sizing agents, coatings,pH buffers, bleaches, enzymes, peroxides, softeners, etc.

[0085] 7. Apparatus for Adding Aqueous Detergent Formulations

[0086] In general, the desired mode of injection into the machine iscarried out during the cleaning cycle. It is important that the additionof the detergent is accomplished in a fashion to produce copious mixingof the detergent with the CO₂ containing wash fluid prior to exposure ofthe items to be cleaned. Useful components to this end include but arenot limited to static mixers, dynamic mixers, centrifugal pumps,pressure drop orifices, pipe constrictions, narrow sections of tubing,control valves, and additional equipment beneficial in providing highshear mixing. The sheared fluid composed of the CO₂ wash fluid, water,surfactants, cosolvents and adjuncts is exposed to the articles to becleaned. Water that cannot be stabilized in the system in the form of anoptically clear emulsion, dispersion or solution depletes evenly onfabric surfaces facilitating the dissolution of water-soluble soils. Theformulations are typically used at levels between 0.1 and 10% of thetotal wash fluid volume and preferably between 0.2 and 2.0%.

[0087] Cleaning of articles by contact with a liquid compositioncontaining carbon dioxide, water, a surfactant, and an organic cosolventhas been previously disclosed. Injection of water or water andsurfactant separate from the CO₂ and cosolvent in the present inventionhas been determined to be advantageous in some cases. Organic cosolventshave been disclosed as solvent modifiers that serve to increase thesolvent potential of liquid CO₂. Fixing the level of cosolvent in acleaning system may be desired to control the level of solvency of theprimarily CO₂ containing system. However, flexibility in the additionquantities of water or water and surfactant may be desired based onefforts to control the water content of a given cleaning cycle. Loadsprimarily composed of hydrophilic fabrics such as cotton and cottonblends can require more water for dissolution of water-soluble soilsthan loads primarily composed of hydrophobic fabrics such as polyesterand other synthetic materials.

[0088] It is an additional component of this invention that temperaturecan be used to control partitioning of water from the bath to items tobe cleaned or conversely from the items cleaned to the bath. The“tunable” nature of liquid and supercritical carbon dioxide is wellknown. The solubility of water in CO₂ varies considerably as a functionof temperature. With this feature the aqueous detergent can be injectedto the machine at a temperature between 65 and 80° F. where watersolubility is relatively low, throughout the cleaning cycle thetemperature of the fluid can be lowered to increase the solubility ofthe water in the bath. Water at the surfaces of the items will thenpartition into the bath. Conversely, the detergent can be injected intothe wash fluid at a lower temperature where solubility is higher and thetemperature can be raised to lower water solubility, resulting inpartitioning of water from the bath to the fabric throughout the washcycle.

[0089] A system for the addition of aqueous (or nonaqueous) detergentformulations and the like to a carbon dioxide dry cleaning system underturbulent or high shear conditions is disclosed in FIG. 2. The systemcomprises a high pressure wash vessel 11 and a drive means 20 asdescribed in connection with FIG. 1 above. In addition, the systemincludes a filter 30, a carbon dioxide cleaning solution drain line 31interconnecting the wash vessel to the filter, a carbon dioxide cleaningsolution supply line 32 connecting the filter to the wash vessel, and ahigh pressure pump 33 operably connected to the drain line. The filtermay be a lint filter and/or carbon filter, or any other suitable filter.

[0090] A detergent formulation reservoir 34 is provided, with adetergent formulation supply line 35 connecting the reservoir to thecarbon dioxide cleaning solution supply line. A second high pressurepump 36 operably connected to the detergent formulation supply line isprovided to transfer detergent formulation from the detergentformulation reservoir into the carbon dioxide cleaning solution underhigh shear conditions.

[0091] High pressure pumps simply refer to pumps that are capable ofpumping liquid carbon dioxide. The closed system and maintaining thetemperature below 31 degrees Centigrade ensures that the CO₂ remainsliquid. Impeller pumps (or centrifugal or rotating vane pumps), suitablefor the first high pressure pump, do not operate under conditions wherethere can be significant differential pressures across the pump. Wheretheir is a significant pressure differential across the pump (as in thesecond high pressure pump), such pumps are typically positivedisplacement pumps such as piston pumps or diaphragm pumps.

[0092] In an alternative embodiment, the detergent formulation supplyline 35 could be connected to the drain line 31, but the detergentformulation would then pass through the filter and potentially bedepleted on the filter. Optionally, control valves and a bypass line,dead-head, or other bypass means can be provided to bypass the filterduring addition of the formulation.

[0093] In operation, the aforesaid apparatus provides a method of addinga detergent formulation to a carbon dioxide dry cleaning system. Inoperation, a continuous stream of liquid carbon dioxide cleaningsolution is pumped from the wash vessel through the filter and back tothe wash vessel to clean articles in the wash vessel, and the detergentformulation is added into the continuous stream of liquid carbon dioxideat a point downstream of the filter and upstream of the wash vessel atjunction 37 to introduce the detergent formulation. Since pumping of thecontinuous stream by the first pump 33 is preferably carried out at arate of about 10 or 20 to 200 or 300 gallons per minute, turbulence willoccur at least a junction 37 when the detergent formulation is pumpedinto the stream. Those skilled in the art will appreciate how tospecifically configure size and shapes of the pipes and the rate ofpumping of the detergent formulation and continuous stream to facilitateturbulence and corresponding mixing.

[0094]FIG. 3 represents an apparatus that employs both the systemdescribed in FIG. 1 and the system described in FIG. 2. Since manycleaning operations incorporate different types of surfactants, some ofwhich may be maintained in the carbon dioxide liquid in significantquantities from wash to wash and others of which may be depleted ontothe articles to be cleaned and/or the filters from wash to wash, thecombination of both types of detergent formulation addition systems isadvantageous, particularly where different formulations are addedthrough each addition system. Like parts in FIG. 3 are assigned likenumbers as compared to FIGS. 1 and 2 above.

[0095] 8. Additional Drain Control Means

[0096]FIG. 4 illustrates an apparatus similar to FIG. 1, except that adifferent drain control system is provided. The system comprises a highpressure wash vessel 51 (i.e., a wash vessel that is capable ofcontaining liquid carbon dioxide), an auxiliary vessel 52, and a drainline 53 connecting the auxiliary vessel to the wash vessel. Theauxiliary vessel is positioned above the wash vessel so that thecontents of the auxiliary vessel can be transferred by gravity to thewash vessel. Optionally, but preferably, a vent line 54 connects theauxiliary vessel to the wash vessel to provide gas-side communicationtherebetween. A detergent reservoir 55 is provided, and a detergentsupply line 56 is provided connecting the detergent reservoir to theauxiliary vessel. Valve 58 is provided to control the system, typicallyby closing the valve during the wash cycle or whenever the wash vesselis pressurized. A pump 59, which is preferably an inexpensive, lowpressure pump, is provided to fill the auxiliary vessel from thedetergent reservoir. The wash vessel may contain a rotating basketdriven by any suitable drive means 60, including but not limited to aturbine drive, a direct motor drive, an internal or external electricmotor, etc.

[0097] The drain line contains a raised portion 62 which functions as avalve, with a corresponding inlet portion 63 and outlet portion 64. Thesystem uses a low pressure pump on the soap supply system, whichrequires that the auxiliary vessel be at essentially ambient pressurewhen it is being filled, and likewise requires the wash vessel to be atessentially ambient pressure. When the level of detergent in theauxiliary vessel goes above the level of the raised portion 62,represented by line 61, then the contents of the wash auxiliary vesselraises in inlet portion 63 through the raised portion 62 is siphonedinto the wash vessel through outlet portion 64. In the alternative, thedetergent in the auxiliary vessel can be raised to the raised level butnot above the raised level and CO₂ gas can be pumped into the washvessel to swell the detergent formulation, bring it above the raisedlevel and cause the detergent formulation to drain into the wash vessel.

[0098] A still further embodiment is illustrated by FIG. 5. This systemis similar to that of FIG. 4, but differs in how it the auxiliary vesselempties, and in fact illustrates a variety of different emptyingmechanisms, any one of which could be implemented. The system comprisesa high pressure wash vessel 71 (i.e., a wash vessel that is capable ofcontaining liquid carbon dioxide), an auxiliary vessel 72, and a drainline 73 connecting the auxiliary vessel to the wash vessel. Theauxiliary vessel is again positioned above the wash vessel. A vent linewhich also serves as a back pressure line 74 connects the auxiliaryvessel to the wash vessel to provide gasside communication therebetween.A detergent reservoir 75 is provided, and a detergent supply line 76 isprovided connecting the detergent reservoir to the auxiliary vessel.Valve 78 is provided to control the system, typically by closing thevalve during the wash cycle. A pump 79, which is preferably aninexpensive, low pressure pump, is provided to fill the auxiliary vesselfrom the detergent reservoir. The wash vessel may contain a rotatingbasket driven by any suitable drive means 80, including but not limitedto a turbine drive, a direct motor drive, an internal or externalelectric motor, etc. The drain line contains a raised portion 82 whichfunctions as a valve as in FIG. 4 above, with a corresponding inletportion 83 and outlet portion 84. In this case, however, as will beapparent from the detergent transfer mechanism described below, all thatis required is that the auxiliary vessel not drain by gravity prior toits contents being pushed into the wash vessel; thus, the raised portionin the drain line could be eliminated, and the auxiliary vessel simplypositioned below the wash vessel. The system of FIG. 5 further includesa high pressure pump 90 and filter 91 through which the carbon dioxidecleaning medium is cycled via line 92 during the cleaning cycle.

[0099] There are three options by which the contents of auxiliary vessel72 may be transferred to wash vessel 71, as follows:

[0100] (A) First, simple back pressure from valve 101 (or otherbackpressure means such as a constricted section of pipe) from flowthrough line 74 into tank 72 will flush the contents of the auxiliarytank into the wash tank via line 73A.

[0101] (B) In addition or in alternative to the foregoing, line 74Bcould be provided so that the detergent formulation in auxiliary vesssel72 is co-mixed with the main carbon dioxide fluid in line 92 before itis returned to wash vessel 71.

[0102] (C) Finally, in addition to or in alternative to the foregoing,line 73C may be provided and the flush stream from the auxiliary vesseland combined with the main liquid in line 92 prior to (as illustrated)or after the high pressure pump 90.

[0103] In all of the foregoing, in alternative to using a flush linethrough line 74, a gas inlet line 102 from a high pressure gas source103 (e.g., a system still, the gas side of a compressor, a compressedgas vessel, etc.), and high pressure gas allowed to enter the auxiliaryvessel to flush or push the contents thereof into the wash vessel 71 orline 92. In addition to or in alternative to the foregoing, a heater(not shown) can be provided in operative association with the auxiliaryvessel to heat the contents of the auxiliary vessel and cause thecontents thereof to expand into the wash vessel or line 92.

[0104] While the present invention is described above with the use of ahigh pressure pump for pumping liquid carbon dioxide from the washvessel drain line through a filter and back to the wash vessel, it willbe appreciated that other fluid transfer means for transfering theliquid carbon dioxide wash medium can also be employed as an alternateto, or as a supplement to, a high pressure pump. Such other fluidtransfer means include, but are not limited to, a system for supplying asecond compressed gas to push the densified liquid carbon dioxide fromone location to another in the system as described in U.S. Pat. No.5,412,958 to Iliff et al., and the use of multiple pressure tanks asdescribed in U.S. Pat. No. 5,904,737 to Preston et al., the disclosuresof both of which are incorporated by reference herein in their entirety.

[0105] 9. Cleaning

[0106] The details of the overall cleaning process will depend upon theparticular apparatus employed, as discussed in greater detail above. Inpractice, in a preferred embodiment of the invention, an article to becleaned and a liquid dry cleaning composition as given above arecombined in a closed drum. The liquid dry cleaning composition ispreferably provided in an amount so that the wash vessel contains both aliquid phase and a vapor phase (that is, so that the drum is notcompletely filled with the article and the liquid composition). Thearticle is then agitated in the vessel, preferably so that the articlecontacts both the liquid dry cleaning composition and the vapor phase,with the agitation carried out for a time sufficient to clean thefabric. The cleaned article is then removed from the drum. The articlemay optionally be rinsed (for example, by removing the composition fromthe drum, adding a rinse solution such as liquid CO₂ (with or withoutadditional ingredients such as water, cosolvent, etc.) to the drum,agitating the article in the rinse solution, removing the rinsesolution, and repeating as desired), after the agitating step and beforeit is removed from the drum. The dry cleaning compositions and the rinsesolutions may be removed by any suitable means, including both drainingand venting.

[0107] The present invention is explained in greater detail in thefollowing non-limiting examples.

EXAMPLE 1 Nonaqueous Detergent Formulation

[0108] An example of an essentially nonaqueous liquid carbon dioxide drycleaning system that can be used to carry out the present invention is amixture that contains:

[0109] 4.2% ISOPAR M™ organic solvent;

[0110] 0.24% water;

[0111] 0.196% TRITON™ RW-20 (commercial detergent available from UnionCarbide; a secondary amine ethoxylate);

[0112] 0.048% TRITON™ GR-7M detergent (a commercial detergent of UnionCarbide; sodium dioctyl sulfosuccinate in aromatic and aliphatichydrocarbons); and

[0113] 0.48% TERGITOL™ 15-S-3 detergent (a commercial detergent of UnionCarbide; a secondary alcohol ethoxylate; and

[0114] carbon dioxide to balance.

[0115] The formulation (all ingredients except carbon dioxide) is addedto the liquid carbon dioxide by adding it to the wash tank through anauxiliary vessel as described in connection with FIG. 1 above. Thus, forexample, the concentration of the ingredients in the mixture containedin the auxiliary vessel would be: 85.7% ISOPAR M™ solvent; 4.5% water;0.90% TRITON™ RW-20 detergent; 0.90% TRITON™ GR-7M detergent; and 0.80%TERGITOL™ 15-S-3 surfactant.

EXAMPLE 2 Nonaqueous Detergent Formulation

[0116] An additional example of a liquid carbon dioxide dry cleaningsystem that can be used to carry out the present invention is a mixturethat contains:

[0117] 3.07% ISOPAR M™ organic solvent;

[0118] 1.32% DPMA (diopropylene glycol monomethyl ether acetate);

[0119] 0.087% water;

[0120] 0.023% TRITON™ GR-7M detergent (a commercial detergent of UnionCarbide; sodium dioctyl sulfosuccinate in aromatic and aliphatichydrocarbons); and

[0121] 0.5% TERGITOL™ 15-S-3 detergent (a commercial detergent of UnionCarbide; a secondary alcohol ethoxylate); and

[0122] carbon dioxide to balance.

[0123] The formulation (all ingredients except carbon dioxide) is addedto the liquid carbon dioxide by adding it to the wash tank through anauxiliary vessel as described in connection with FIG. 1 above. Thus, forexample, the concentration of the ingredients in the mixture containedin the auxiliary vessel would be: 61.4% ISOPAR M™ solvent; 26.4% DPMA,1.74% water; 0.46% TRITON™ GR-7M detergent; and 10.0% TERGITOL™ 15-S-3surfactant.

EXAMPLE 3 Aqueous Detergent Formulations

[0124] A series of different aqueous detergent formulations suitable forliquid carbon dioxide dry-cleaning are given as Examples A through Fbelow. Percentages are given as Percent volume/volume.

[0125] Formulation A

[0126] 95% water;

[0127] 3% TERGITOL 15-S-3™ surfactant;

[0128] 1% TERGITOL 15-S-7™ surfactant; and

[0129] 1% Dipropylene glycol monobutyl ether.

[0130] Formulation B

[0131] 65% water;

[0132] 30% ISOPAR M™ organic solvent;

[0133] 3% TERGITOL 15-S-3™ surfactant;

[0134] 1% TERGITOL 15-S-7™ surfactant;

[0135] 0.50% AOT surfactant; and

[0136] 0.50% TERGITOL 15-S-15™ surfactant.

[0137] Formulation C

[0138] 95.5% water;

[0139] 3% TERGITOL 15-S-3™ surfactant;

[0140] 0.25% TERGITOL 15-S-15™ surfactant;

[0141] 0.25% TERGITOL TMN-6™ surfactant; and

[0142] 1.5% Cetyltrimethylammonium chloride.

[0143] Formulation D

[0144] 65.75% water;

[0145] 25% ISOPAR M™ organic solvent;

[0146] 5% hexylene glycol;

[0147] 3.0% TERGITOL 15-S-3™ surfactant;

[0148] 1.0% 3-Dodecyldimethylamminiopropane-1-sulfonate;

[0149] 0.25% TERGITOL TMN-6™ surfactant.

[0150] Formulation E

[0151] 96% water;

[0152] 2% TERGITOL 15-S-3™ surfactant; and

[0153] 2% TERGITOL 15-S-7™ surfactant.

[0154] Formulation F

[0155] 94% water;

[0156] 3% Dipropylene glycol monobutyl ether;

[0157] 2% TERGITOL 15-S-7™ surfactant; and

[0158] 1% PDMS-g-PEG (polydimethyl siloxane-graft-polyethylene glycol

[0159] copolymer) (500 g/mol PDMS with 350 g/mol PEG).

EXAMPLE 4 Addition of Aqueous Detergent Formulation A

[0160] 1.0 liters of a formulation such as that described in Formula Ain Example 3 is injected into a CO₂ based dry cleaning machine with aliquid volume of approximately 80 gallons such that the formulation isfed to the low pressure side of a centrifugal pump. The pump is usedprimarily to transfer fluid from storage to the cleaning wheel and back,and to circulate the cleaning fluid through appropriate filters and heatexchangers. In this case the pump also serves to mix and shear the addeddetergent prior its transport to the cleaning vessel. The well-mixeddetergent is then carried into the vessel by the flow of the wash fluidand water that cannot be stabilized in the wash fluid is evenly depletedon the garments to facilitate aqueous detergency.

EXAMPLE 5 Addition of Aqueous Detergent Formulation

[0161] 1.5 liters of a formulation such as that described in Formula Bin Example 3 is injected into a CO₂ based dry cleaning machine such thatthe formulation is fed to the high-pressure side of a circulating pump.The detergent is carried by the flow of the wash fluid through a staticmixing tube prior to it transport to the cleaning vessel containingarticles to be cleaned. The well-mixed detergent is then carried intothe vessel and water that cannot be stabilized in the wash fluid isevenly depleted on the garments to facilitate aqueous detergency.

EXAMPLE 6 Addition of Aqueous Detergent Formulation

[0162] 1.0 liters of a formulation such as that described in Formula Fin Example 3 is injected into a CO₂ based dry cleaning machine such thatthe formulation is fed to the high-pressure side of a circulating pump.The temperature of the bath during the injection of the detergent is 70°F. Throughout the cycle the temperature of the bath is lowered to 50° F.by the end of the cleaning cycle.

EXAMPLE 7 Addition of Aqueous Detergent Formulation

[0163] 1.0 liters of a formulation such as that described in Formula Ein Example 3 is injected into a CO₂ based dry cleaning machine such thatthe formulation is fed to the low-pressure side of a centrifugal pump.The wash fluid in the system is composed of approximately 95% liquid CO₂and 4% of an organic co-solvent. The sheared mixture is then carriedinto the cleaning vessel where the bath temperature is 45° F. Throughoutthe cycle the temperature of the bath is raised to 70° F.

[0164] The foregoing is illustrative of the present invention, and isnot to be construed as limiting thereof. The invention is defined by thefollowing claims, with equivalents of the claims to be included therein.

That which is claimed is:
 1. A system for the addition of detergentformulations to a carbon dioxide cleaning apparatus, said systemcomprising: (a) a high pressure wash vessel; (b) an auxiliary vessel;(c) a drain line connecting said auxiliary vessel to said wash vessel;(d) a vent line connecting said auxiliary vessel to said wash vessel;(e) a detergent reservoir; (f) a detergent supply line connecting saiddetergent reservoir to said auxiliary vessel; and (g) drain controlmeans operatively associated with said drain line for controlling thetime of draining of detergent formulation from said auxiliary vesselinto said wash vessel.
 2. A system according to claim 1, furthercomprising a low-pressure pump operatively associated with saiddetergent supply line for transferring detergent from said reservoir tosaid auxiliary vessel.
 3. A system according to claim 2, wherein saidlow-pressure pump is a peristaltic pump or a piston pump.
 4. A systemaccording to claim 1, wherein said drain control means comprises a drainvalve.
 5. A system according to claim 4, wherein said auxiliary vesselis positioned above said wash vessel so that detergent formulation canbe transferred from said auxiliary vessel to said wash vessel bygravity.
 6. A method for the controlled addition of a low-water contentdetergent formulation to a carbon dioxide dry cleaning system, saidmethod comprising: providing a carbon dioxide cleaning apparatuscomprising a wash vessel and a separate auxiliary vessel; (a) reducingthe pressure in said wash vessel and said auxiliary vessel; then (b)adding a detergent formulation to said auxiliary vessel, said detergentformulation comprising (i) at least 30 percent organic co-solvent, (ii)at least 1 percent surfactant; and (ii) not more than 10 percent water;then (c) increasing the pressure in said wash vessel so that liquidcarbon dioxide can be pumped therethrough to clean articles in said washvessel; and then (d) transferring said detergent formulation from saidauxiliary vessel to said wash vessel to facilitate the cleaning ofarticles therein.
 7. A method according to claim 6, wherein said addingand transferring steps are carried out while maintaining gas-sidecommunication between said wash vessel and said auxiliary vessel.
 8. Amethod according to claim 6, wherein said transferring step is carriedout by gravity drainage.
 9. A method according to claim 6, wherein saidadding step is carried out by pumping said detergent formulation intosaid auxiliary vessel.
 10. A method according to claim 6, wherein saidpumping step is carried out with a low pressure pump.
 11. A system forthe addition of aqueous detergent formulations to a carbon dioxide drycleaning system under turbulent conditions, said system comprising: (a)a high pressure wash vessel; (b) a filter; (c) a carbon dioxide cleaningsolution drain line interconnecting said wash vessel to said filter; (d)a carbon dioxide cleaning solution supply line connecting said filter tosaid wash vessel; (e) a first high pressure liquid transfer meansoperably associated with said drain line; (f) a detergent formulationreservoir; (g) a detergent formulation supply line connecting saidreservoir to said carbon dioxide cleaning solution supply line or drainline; and (h) a second high pressure pump operably connected to saiddetergent formulation supply line for transferring detergent formulationfrom said detergent formulation reservoir into said carbon dioxidecleaning solution under turbulent conditions.
 12. A system according toclaim 11, wherein said filter comprises a carbon filter.
 13. A systemaccording to claim 11, wherein said filter comprises a lint filter. 14.A system according to claim 11, wherein said first high pressure liquidtransfer means is a pump.
 15. A system according to claim 11, whereinsaid second high pressure pump is a piston or diaphragm pump.
 16. Amethod for the addition of aqueous detergent formulations to a carbondioxide dry cleaning system under turbulent conditions, said methodcomprising: (a) providing a carbon dioxide cleaning apparatus comprisinga wash vessel and a filter; (b) pumping a continuous stream of liquidcarbon dioxide cleaning solution from said wash vessel through saidfilter and back to said wash vessel to clean articles in said washvessel; and (c) adding a detergent formulation into said continuousstream of liquid carbon dioxide to introduce the detergent formulationinto said continuous stream, with said detergent formulation comprising(i) at least 20 percent water, and (ii) at least 1 percent surfactant,so that water in said detergent formulation is dispersed in said liquidcarbon dioxide prior to entry into said wash vessel, without depletionin said filter.
 17. A method according to claim 16, wherein said step ofpumping a continuous stream of liquid carbon dioxide is carried out at arate of about 10 to 300 gallons per minute.
 18. A method according toclaim 16, wherein said step of pumping a continuous stream of liquidcarbon dioxide is carried out at a rate of about 20 to 200 gallons perminute.
 19. A method according to claim 16, wherein said adding step iscarried out by pumping said detergent formulation into said continuousstream.
 20. A method according to claim 19, wherein detergentformulation and said continuous stream are combined under turbulentconditions.
 21. A carbon dioxide dry cleaning system that permits theaddition of aqueous detergent formulations to a carbon dioxide drycleaning system under turbulent conditions, and also permits thecontrolled addition of detergent formulations and the like, said systemcomprising: (a) a high pressure wash vessel; (b) a filter; (c) a carbondioxide cleaning solution drain line interconnecting said wash vessel tosaid filter; (d) a carbon dioxide cleaning solution supply lineconnecting said filter to said wash vessel; (e) a first high pressureliquid transfer means operably associated with said drain line; and (f)a first detergent formulation addition system comprising (i) a detergentformulation reservoir; (ii) a detergent formulation supply lineconnecting said reservoir to said carbon dioxide cleaning solutionsupply line or drain line; and (iii) a second high pressure pumpoperably connected to said detergent formulation supply line fortransferring detergent formulation from said detergent formulationreservoir into said carbon dioxide cleaning solution under turbulentconditions; and (g) a second detergent formulation addition systemcomprising (i) an auxiliary vessel; (ii) a drain line connecting saidauxiliary vessel to said wash vessel; (iii) a vent line connecting saidauxiliary vessel to said wash vessel; (iii) a detergent reservoir; and(iv) a detergent supply line connecting said detergent reservoir to saidauxiliary vessel.
 22. A system according to claim 21, wherein saidfilter comprises a carbon filter.
 23. A system according to claim 21,wherein said filter comprises a lint filter.
 24. A system according toclaim 21, wherein said first high pressure liquid transfer meanscomprises a pump.
 25. A system according to claim 21, wherein saidsecond high pressure pump is an impeller pump.
 26. A system according toclaim 21, further comprising a low-pressure pump operatively associatedwith said detergent supply line for transferring detergent from saidreservoir to said auxiliary vessel.
 27. A system according to claim 26,wherein said low-pressure pump is a peristaltic pump or a piston pump.28. A system according to claim 21, further comprising a drain valveoperatively associated with said drain line for controlling the time ofdraining of detergent formulation from said auxiliary vessel into saidwash vessel.
 29. A system according to claim 28, wherein said auxiliaryvessel is positioned above said wash vessel so that detergentformulation can be transferred from said auxiliary vessel to said washvessel by gravity.